This application claims benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 2003-44840 and Korean Patent Application No. 2003-45387, respectively filed on Jul. 3, 2003 and Jul. 4, 2003 in the Korean Intellectual Property Office, the entire disclosures of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an electrophotographic printer. More particularly, the present invention relates to a waste toner transfer apparatus to transfer waste toner generated during a printing process to a waste toner storage container and an electrophotographic printer adopting the same.
2. Description of the Related Art
In an image forming process of an electrophotographic printer, when an exposure unit scans light corresponding to image information onto a photoreceptor that is charged to a predetermined electric potential, an electrostatic latent image is formed on the photoreceptor. A developing unit supplies toner to the electrostatic latent image to form a toner image. Generally, four developing unites containing toners for cyan, magenta, yellow, and black colors are needed for a color electrostatic latent printer. The toner image is transferred directly onto a recording medium, or via an intermediate medium, from the photoreceptor. While the recording medium passes through a fusing unit, the toner image is fused onto the recording medium by heat and pressure. As a result of the above processes, a mono or color image is printed on the recording medium.
While a wet type electrophotographic printer uses a wet developer formed by dispersing toner powder in a liquid carrier, a dry type electrophotographic printer uses toner powder as a developer. Waste toner remaining on the photoreceptor or the intermediate transfer medium during the image forming process is removed therefrom. The removed waste toner is transferred to a waste toner storage container. The electrophotographic printer typically includes a waste toner transfer apparatus for transferring waste toner to the waste toner storage container.
FIG. 1 is a view illustrating a conventional waste toner transfer apparatus. Referring to FIG. 1, a cleaning apparatus 1 removes waste toner from the photoreceptor or intermediate transfer medium. The waste toner removed by the cleaning apparatus 1 is transferred by a waste toner transfer apparatus 2 to a waste toner storage container (not shown). The waste toner enters a duct 4 through an inlet portion 3. A shaft 5 rotated by a drive motor 6 is installed in the duct 4 and a conveying coil 7 is coupled to an end portion of the shaft 5. The duct 4 and the waste toner storage container are connected by a pipe 8. The conveying coil 7 is installed to extend through the inside of the pipe 8. The waste toner entering the duct 4 through the inlet portion 3 is transferred by the conveying coil 7 to the waste toner storage container along the pipe 8.
FIG. 2 is a more detailed view of section “A” of the conveying coil shown in FIG. 1. The waste toner transferred along the conveying coil 7 falls in the inner space of the conveying coil 7 as indicated by arrows shown in FIG. 2. Thus, the inner space of the conveying coil 7 must be filled in order for the conveying coil 7 to transfer the waste toner to the waste toner storage container. That is, when the inside of the pipe 8 is filled with the waste toner, the waste toner is transferred to the waste toner storage container as the conveying coil 7 rotates. In this state, the density of the waste toner inside the pipe 8 gradually increases. In particular, when the waste toner is left in a high temperature and high humidity environment for a long time, the waste toner becomes solidified. Then, even when the conveying coil 7 rotates, the waste toner is not transferred and the conveying coil 7 may be destroyed or the drive motor 6 rotating the conveying coil 7 can become stalled due to an overload. Also, since the waster toner is not transferred, the waste toner is accumulated in the cleaning unit 1.